Man, there needs to be a sequel and it's already overdue. My problem is barely understanding anything, and yes, I for the most part remember the plot of Alien 1. To link together a 2010+ film to one made just about 30+ years before it is rough for a number of reasons. The '70s cult hit created a lot to live up to and link to, and in general, this did a good job.
I'd say that there is some awkward or weak or unneeded character development and that would be one of the worst parts about the film, other than that, this film is just great.